And the second then arrived shortly before the hour mark as Ferreyra benefited from Pepe Reina's generous goalkeeping.

Napoli - who had started with star man Dries Mertens on the bench - hit back through an Arkadiusz Milik penalty, but a leveller evaded Maurizio Sarri's men and they already look to be in trouble after one group game.

Taison dragged an early effort wide for the hosts and Milik's instant response was a low strike that almost crept inside Andriy Pyatov's near post.

But it was Shakhtar who struck first after quarter of an hour, Taison this time finding the bottom-right corner after Ferreyra had flicked Darijo Srna's pass on into his path.

And Taison quickly went chasing a second, but found Reina out of his goal and alert to block the finish as he ran clear.

Napoli belatedly enjoyed some possession and Raul Albiol nodded over from a tight angle.

An equaliser almost arrived in bizarre fashion as Ivan Ordets swiped at a left-wing cross and sent the ball arcing over his own goalkeeper, landing just wide to the relief of the Shakhtar defender, before Pyatov, at full stretch, turned away a curling Lorenzo Insigne shot.

The home side had by now adopted a counter-attacking style and, after a slower start to the second half, it paid dividends.

Ferreyra had fired wide moments earlier, but he made no mistake as Taras Stepanenko's deep cross cleared Reina and left the forward with a simple header into the unguarded goal.